Some of known physical quantity measuring devices include communication units through which measurement data is outputted to an outside.
A typical example of such a physical quantity measuring device in a form of a pressure measurement device includes: a housing; a converter provided to the housing and configured to generate electric signals based on a pressure at an inlet; and a data communication device connected to the converter to transmit wireless signals in accordance with the electric signals (Patent Literature 1: JP-A-2006-510035).
Another typical example of the physical quantity measuring device in a form of a temperature measurement unit includes: a closed housing that houses a sensor element for detecting physical quantity (e.g. temperature) and a memory storing the data detected by the sensor element; and an interface disposed on a surface of the housing (Patent Literature 2: JP-B2-3756969).
Patent Literature 2 discloses that, when a temperature measurement unit is inserted into a recess of a communication unit, the measurement data stored in the memory is transferred to a PC and the like through the communication unit using an optical communication.
The physical quantity measuring device for measuring pressure and temperature requires a zero point calibration, a contact point output setting and the like after the physical quantity measuring device is assembled. The calibration and setting are performed by operating an electronic calibration unit (e.g. a volume adjuster) provided on a circuit board inside the measuring device using a tool such as a screwdriver.
In addition, since the wireless communication is easily affected by disturbances (e.g. electric wave noise and optical noise), it is necessary to furnish an environment capable of stable communication. However, the possible problem associated with the disturbances is avoided by increasing the number of retries for communication.
Though Patent Literatures 1 and 2 disclose an arrangement for outputting the measurement data to the outside through a communication unit, the details of the setting for an electronic calibration unit are not disclosed. Thus, when a zero point calibration and the like are to be performed, a volume adjuster has to be operated using a screwdriver, so that the calibration work becomes troublesome and complicated waterproof structure is required.
Further, Patent Literatures 1 and 2 do not mention the stability of the wireless communication. Thus, whether or not the communication is securely performed is usually checked by an error analysis of communication data (using a check sum, parity check and the like), and it is not checked whether the stable communication environment is furnished or not.